The present invention relates to fixing devices for removable armrests, and to seat devices including such fixing devices.
More particularly, the invention provides a fixing device for a removable armrest, the device comprising a rigid cylindrical support shaft and a rigid housing, one for fixing to an armrest and the other to a seat, at least one locking member projecting laterally from said support shaft, the housing extending for a certain distance along a central axis and comprising:
a plastics material ring having a cylindrical tubular duct extending along the central axis between a rear end and a front end which is open and adapted to receive the support shaft, enabling said support shaft to turn about the central axis while said support shaft is being mounted, the plastics material ring also comprising a rearwardly-open locking recess adapted to receive the locking member of the support shaft and to co-operate by abutment with said locking member to prevent relative pivoting between the support shaft and the housing once said support shaft is mounted in said housing;
a metal reinforcing strength member surrounding the plastics material ring in contact with the tubular duct of said plastics material ring; and
a return spring adapted to urge the support shaft forwards when said support shaft is received in the tubular duct.
Document FR-A-2 789 142 describes an example of such a fixing device, in which the locking housing is completely defined by the ring of plastics material. That fixing device gives entire satisfaction, but it nevertheless suffers from the drawback that the central ring of plastics material runs the risk of being severely stressed in use, which can degrade said central ring if a large pivot torque is applied between the support shaft and the housing. Furthermore, the support shaft is supported by ribs on the plastics material ring over a small fraction of its length, thereby also limiting the mechanical strength of the armrest mount.
The present invention seeks in particular to mitigate that drawback.
To this end, the invention provides a fixing device of the kind in question:
wherein the tubular duct of the plastics material ring is adapted to co-operate by receiving the support shaft without clearance over a major portion of the length of the housing, said tubular duct having at least one axial slot which extends between an open front end opening out in the front end of said tubular duct and a closed rear end, and the tubular duct of the plastics material ring further having at least one circumferential slot which extends between a first end communicating with the rear end of the axial slot and a second end communicating with the locking recess, said axial and circumferential slots being adapted to receive the locking member of the support shaft when the support shaft is mounted in the housing; and
wherein the metal strength member is adapted to co-operate with said locking member of the support shaft by coming into abutment therewith when said locking member is to be found in the locking recess of the housing so as to prevent relative pivoting between the support shaft and the housing about the central axis.
By means of these dispositions, the support shaft is well supported by the tubular duct of the plastics material ring, which duct is itself reinforced by the metal strength member. In addition, said metal strength member takes up the pivot torque between the support shaft and the housing when said support shaft is mounted on the housing, such that the pivot torque applies hardly any stress to the plastics material ring.
In preferred embodiments of the invention, one or more of the following dispositions can optionally be used:
the metal strength member of the housing has an annular side wall surrounding the tubular duct, and an annular front wall extending radially inwards from said side wall at the front end of the tubular duct, said front wall including at least a first notch in correspondence with said at least one axial slot of the plastics material ring to allow the locking member of the support shaft to pass through, and said front wall being extended axially rearwards by folded reinforcing tabs bearing radially against the tubular duct, at least one of the tabs co-operating with said locking member of the support shaft by coming into abutment therewith when said locking member is in the locking recess of the housing so as then to prevent relative pivoting between the support shaft and the housing about the central axis in at least one angular direction;
the reinforcing tabs are engaged in axial longitudinal grooves formed on the outside of the tubular duct in correspondence with said reinforcing tabs in such a manner as to prevent relative pivoting between the plastics material ring and the metal strength member;
each of the reinforcing tabs has first and second longitudinal edges parallel to the central axis, at least a first one of said reinforcing tabs extending so as to slope circumferentially and radially towards the inside in a first angular direction from its first longitudinal edge to its second longitudinal edge, the first longitudinal edge of said first reinforcing tab co-operating with an edge defined by the corresponding axial groove of the tubular duct by coming into abutment therewith to prevent the plastics material ring from pivoting relative to the metal strength member in a second angular direction opposite to the first angular direction, and at least a second one of said reinforcing tabs extending circumferentially and radially inwards in said second angular direction from its first longitudinal edge to its second longitudinal edge, the second longitudinal edge of said second reinforcing tab co-operating with an edge defined by the corresponding axial groove of the tubular duct by coming into abutment therewith to prevent the plastics material ring from pivoting relative to the metal strength member in said first angular direction;
the plastics material ring has a flange extending radially towards from the front end of the tubular duct, said flange including at least one notch in correspondence with the first notch of the front wall of the metal strength member to receive said at least one locking member while the support shaft is being mounted in the housing;
the locking recess is defined by a cutout formed in the tubular duct of the plastics material ring and extending axially forwards from the second end of the circumferential slot to the flange of said plastics material ring, the front wall of the metal strength member having at least one second notch facing said cutout to receive the locking member of the support shaft when said support shaft is mounted in the housing, the second notch having two substantially radial edges adapted to co-operate angularly with the locking member by coming into abutment therewith to prevent relative pivoting between the support shaft and the housing;
the flange of the plastics material ring includes a radial groove that is closed forwardly and open rearwardly, facing the second notch of the metal strength member, the locking member of the support shaft being adapted to engage in part in said radial groove when said support shaft is mounted in the housing;
the metal strength member has an annular end wall which is secured to the side wall of said metal strength member and which extends radially inwards from said side wall to a cylindrical collar bearing radially against the rear end of the tubular duct; and
the return spring is disposed around the tubular duct of the plastics material ring to bear against the end wall of the metal strength member, said return spring being a helical compression spring adapted to urge the locking member forwards.
Furthermore, the invention also provides a seat device comprising a seat and a removable armrest adapted to be mounted on the seat by means of a fixing device as defined above, the housing being secured to a first element selected from the seat and the removable armrest, and the support shaft being secured to a second element selected from the removable armrest and the seat.